In mattress arrangements, such as in a bed arrangement or other seating or furniture arrangements, a support is provided to act on the weight or part of the weight of a user, wherein the bed distributes the weight from the body of the user over a part of a surface of the device. Depending on how the bed distributes the weight of the user, the bed will appear as being either soft or firm. The degree of firmness of such a bed is dependent on the properties of the elastic elements, such as the spring constant, and how the elastic members have been mounted in the bed, such as the degree of clamping or pre-tensioning. Thus, the firmness of the bed is normally set at the manufacturing of the device.
However, different persons wish and require different firmness. Further, different body parts may require different firmness.
It is known to provide bed arrangements with variable firmness. By inducing deformation to the elastic members to different degrees, the firmness of the device is adjustable. The deformation member has the ability to deform the elastic member independently from the deformation of the elastic member induced by the being. This means that the firmness of the bed is adjustable during initialization, according to the wishes of the user. It is also possible to compensate the firmness of the device for possible changes in the elastic properties of the elastic arrangement over time. Still further, it is known to vary the firmness independently in various zones/sections in a mattress.
Such known solutions are e.g. disclosed in EP 2 245 967 and WO 2009/120270. Both these documents also discloses the possibility of sensing the pressure being applied on different zones, and to control the firmness of different zones automatically, in order to lower the overall pressure.
Further, it is known to provide variation in firmness of a mattress by arranging coil springs on support plates having variable height. The height of the support plates may be controlled by rotatable elements arranged under the support plates, and having an off-centre rotation axis. Hereby, by rotation of the rotatable elements, the plates assume various height positions. Such firmness adjustment means are e.g. discussed in U.S. Pat. No. 3,340,548 and US 2011/0258772. It is also known to use a similar arrangement with support plates having variable height where the height of the support plates may be controlled by displacement members in the form of linear motors, jacks, and other types of lifting mechanism. Such firmness adjustment means are e.g. discussed in AU 55 13 00, U.S. Pat. No. 4,222,137, US 2006/0253994, WO 99/65366 and EP 2 245 967.
It is also known to provide zones having variable firmness realized by inflatable elements, in which the pressure is independently variable by means of pressurization means. Such firmness adjustment means are e.g. discussed in WO 2009/120270.
Further, it is known to realize mattresses with variable firmness by a combination of inflatable elements and other resilient elements, such as coil springs, as is e.g. discussed in U.S. Pat. No. 5,113,539.
May other firmness adjustment means are also feasible, such as by arranging threads through the mattress, whereby the height position and/or tension is variable, such as is e.g. discussed in U.S. Pat. No. 4,667,357.
However, common problems with these previously known bed arrangements with variable firmness are that they are relatively complex, heavy and costly to produce. Further, these known bed arrangements are also often relatively difficult and cumbersome to use. Further, even though these known bed arrangements provide a certain degree of adjustability, this is often inadequate for the users' needs.
It is therefore still a need for a mattress arrangement, and in particular a bed arrangement, with adjustable firmness/height which alleviates the above-discussed problems.